U.S. patent application number 11/714229 was filed with the patent office on 2007-09-20 for drying method of clothes dryer.
This patent application is currently assigned to LG Electronics Inc.. Invention is credited to Seung-Phyo Ahn, Dong-Joo Han, Hyun-Uk Lee, Jung-Wook Moon, Byeong-Jo Ryoo, Chang-Woo Son.
Application Number | 20070214678 11/714229 |
Document ID | / |
Family ID | 37866822 |
Filed Date | 2007-09-20 |
United States Patent
Application |
20070214678 |
Kind Code |
A1 |
Son; Chang-Woo ; et
al. |
September 20, 2007 |
Drying method of clothes dryer
Abstract
Disclosed in a control method of a clothes dryer. The drying
method of a clothes dryer, includes: detecting a temperature of the
air exhausted from a drum; determining a change in water content of
a drying material on the basis of the detected temperature; and
controlling a drying operation according to the water content
change of the drying material. Accordingly, the air temperature in
an exhaust port of a drum is measured, and a water content or a
temperature of a drying material can be determined on the basis of
data about a gradient of the temperature change.
Inventors: |
Son; Chang-Woo; (Buk-Gu,
KR) ; Lee; Hyun-Uk; (Gimhae, KR) ; Ahn;
Seung-Phyo; (Gimhae, KR) ; Han; Dong-Joo;
(Changwon, KR) ; Ryoo; Byeong-Jo; (Changwon,
KR) ; Moon; Jung-Wook; (Gimhae, KR) |
Correspondence
Address: |
KED & ASSOCIATES, LLP
P.O. Box 221200
Chantilly
VA
20153-1200
US
|
Assignee: |
LG Electronics Inc.
|
Family ID: |
37866822 |
Appl. No.: |
11/714229 |
Filed: |
March 6, 2007 |
Current U.S.
Class: |
34/446 ; 34/476;
34/491 |
Current CPC
Class: |
D06F 2105/28 20200201;
D06F 2103/32 20200201; D06F 58/30 20200201; D06F 2103/38 20200201;
D06F 58/38 20200201; D06F 2103/08 20200201 |
Class at
Publication: |
34/446 ; 34/476;
34/491 |
International
Class: |
F26B 3/00 20060101
F26B003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 14, 2006 |
KR |
10-2006-0023715 |
Claims
1. A drying method of a clothes dryer, comprising: detecting a
temperature of the air exhausted from a drum; determining a change
in water content of a drying material on the basis of the detected
temperature; and controlling a drying operation according to the
water content change of the drying material.
2. The method of claim 1, wherein the determining of the water
content change of the drying material uses a temperature change
pattern of the exhausted air over time.
3. The method of claim 1, wherein the determining of the water
content change of the drying material determines the following at
least three periods: a) an initial preheating period of the drying
material; b) a constant rate (isothermal) drying period of the
drying material; and c) an overheating drying period of the drying
material.
4. The method of claim 1, wherein the determining of the water
content change of the drying material comprises obtaining a
gradient of a temperature change over a predetermined period time,
and setting a drying period on the basis of accumulation data of
the gradient change.
5. The method of claim 4, wherein the accumulation data of the
gradient change is obtained by continuously obtaining a gradient of
a temperature change of a predetermined time (predetermined period)
with respect to a unit time.
6. The method of claim 1, wherein in the determining of the water
content change of the drying material, the water content change is
determined on the basis of a gradient change of a temperature
change of the exhausted air.
7. The method of claim 6, wherein a drying operation of the drying
material is controlled with reference to a time point when the
gradient of the temperature change becomes constant, and a time
point when the gradient of the temperature change increases.
8. The method of claim 6, wherein the gradient change
(.DELTA.gradient) of the temperature change of the exhausted air is
determined by the following equation using a maximum gradient (Max)
and a minimum gradient (Min) with respect to a predetermined time
(predetermined period) (T): .DELTA. gradient=(Max(T)-Min(T))/T
Description
RELATED APPLICATION
[0001] The present disclosure relates to subject matter contained
in priority Korean Application No. 10-2006-0023715, filed on Mar.
14, 2006, which is herein expressly incorporated by reference in
its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a drying method of a
clothes dryer, and more particularly, to a drying method of
determining changes in temperature and water content of a drying
material on the basis of a temperature change of the exhausted air
to perform a drying operation.
[0004] 2. Description of the Background Art
[0005] A clothes dryer may be classified into an exhaust type and a
condensation type according to a processing method of humid air
generated as drying materials are dried. The former type of clothes
dryer employs a method of exhausting the humid air from the drier
to the outside, and the latter type of clothes dryer employs a
method of condensing water vapor of the humid air exhausted from
the dryer to remove moisture, and circulating the air into the
dryer.
[0006] In general, an exhaust type dryer includes a drum rotatably
installed in a cabinet, an inlet duct and an outlet duct connected
to the drum, and a heater installed in the air induction duct.
[0007] The external air is introduced into the inlet duct by
driving of a fan, and then is heated by the heater. The heating
temperature reaches up to about 100.degree. C. The hot air is
introduced into the drum in the dryer to dry a drying material
within the drum. Then, the hot air contains moisture of the drying
material during the drying operation, and the hot, humid air is
exhausted to the outside via the exhaust duct.
[0008] The conventional clothes dryer transfers heat to the
introduced air using the heater may desirably reduce the time for
the entire drying operation by the rapid air heating of the heater,
and may have a large capacity, whereas disadvantageously consuming
a large amount of energy for heating the air using the heater.
Particularly, since the drying material is dried by the hot air of
100.degree. C. or higher, damage to the drying material may occur
depending on a kind of the drying material.
[0009] In contrast, the condensation type clothes dryer may be
advantageously manufactured into a built-in type since the exhaust
duct through which the air is exhausted to the outside is
unnecessary. Also, the energy efficiency of the condensation type
clothes dryer is higher than that of the exhaust type one. However,
disadvantageously, the condensation type clothes dryer requires
long time, and it is difficult to manufacture this type of dryer to
have a large capacity.
[0010] For those reasons, an improved clothes dryer having great
energy efficiency and causing no damage to a drying material is
needed, and a more stable drying method with higher efficiency is
also required.
[0011] In the conventional automatic drying method of a clothes
dryer, the time to terminate a drying stroke during a drying
process is determined with respect to a water content of a drying
material set by a user. To determine the water content, a
resistance value change is obtained according to the water content
of the drying material using an electrode sensor.
[0012] However, as illustrated in FIG. 1, an electrode sensor 22 of
a dryer 10 is placed at one side of a front portion within a drum
20, and thus can detect only a drying material placed at the front
side within the drum 20. Consequently, a water content of every
drying material within the drum 20 cannot be detected.
[0013] Also, since the drum 20 is rotated about a horizontal axis,
most of drying materials is moved only vertically within the drum
20, without being moved horizontally, the electrode sensor 22 can
detect only a drying material placed at the front side within the
drum. Thus, a drying material placed at the rear of the drum cannot
contact the electrode sensor 22, and therefore the drying-material
sensing ability of the electrode sensor 22 is deteriorated.
[0014] As for a drying method, as illustrated in FIG. 2, a voltage
change (ERTD) of the electrode sensor 22 is measured, and an
additional drying operation is performed from the time point when a
voltage of the electrode sensor 22 is saturated. In the method of
adding the drying time, a final water content desired by a user may
vary according to a kind of a drying material (e.g., clothes dried
fast, and clothes dried slowly).
[0015] Accordingly, a new type of clothes dryer is required, which
is able to stably and efficiently perform a drying operation,
regardless of a kind or the amount of drying materials.
BRIEF DESCRIPTION OF THE INVENTION
[0016] Therefore, an object of the present invention is to provide
a method of controlling a clothes dryer capable of constantly and
stably performing a drying operation, regardless of the amount and
kind of a drying material.
[0017] Another object of the present invention is to provide a
method of controlling a clothes dryer capable of meeting consumer
demand for a drying level and implementing various drying modes,
without adding complicated elements and greatly changing an
internal structure of a clothes dryer.
[0018] To achieve these and other advantages and in accordance with
the purpose of the present invention, as embodied and broadly
described herein, there is provided a drying method of a clothes
dryer, including: detecting a temperature of the air exhausted from
a drum; determining a change in water content of a drying material
on the basis of the detected temperature; and controlling a drying
operation according to the water content change of the drying
material.
[0019] Preferably, the determining of the water content change of
the drying material determines the following at least three
periods: a) an initial preheating period of the drying material; b)
a constant rate (isothermal) drying period of the drying material;
and c) an overheating drying period of the drying material.
[0020] The foregoing and other objects, features, aspects and
advantages of the present invention will become more apparent from
the following detailed description of the present invention when
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention and together with the description serve to explain
the principles of the invention.
[0022] In the drawings:
[0023] FIG. 1 is a perspective view illustrating an exterior of a
conventional clothes dryer;
[0024] FIG. 2 is a graph for describing a drying method of a
conventional clothes dryer;
[0025] FIGS. 3A and 3B are views illustrating an exterior and an
internal structure of a clothes dryer according to an embodiment of
the present invention;
[0026] FIG. 4 is a graph for describing a principle of a drying
method according to an embodiment of the present invention;
[0027] FIGS. 5A and 5B are graphs showing a water content and a
temperature change in an actual drying process of a drying
material;
[0028] FIG. 6 is a graph showing a temperature change gradient
according to an embodiment of the present invention; and
[0029] FIG. 7 is a flow chart exemplarily illustrating a drying
method according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0030] Reference will now be made in detail to the preferred
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings.
[0031] Referring to FIGS. 3A and 3B, a clothes dryer 10 according
to an embodiment of the present invention includes a sensor 40
detecting a temperature (or, humidity) of exhaust air. The sensor
40 is installed on a flow path of the air discharged from a drum
20, preferably, near to an air flow fan 30.
[0032] The sensor 40 continuously detects a temperature (or
humidity) of the air exhausted from the drum 20 after being heated
by the heater 15, introduced into the drum 20 through an air path
12, and absorbing moisture from a drying material (not shown)
during a drying operation. Data of the detected air temperature (or
humidity) is transmitted to a controller (not shown) such as a
micom mounted within the dryer 10 in real-time.
[0033] The data transmitted to the controller in real-time is used
as a basic material for determining a dried degree change and a
water content of the drying material according to the drying
process.
[0034] Unlike the conventional method of controlling heat from the
heater to a desired temperature simply by determining a dried
degree (or, water content of a drying material) over time of a
drying operation in an existing drier, in the present invention, a
water content of clothes is detected during the drying operation
using a pattern of a temperature (or humidity) change of the air
exhausted from the drum, and a dried degree of the drying material
is determined according to the detected water content change, so as
to control the drying operation of the clothes dryer.
[0035] Hereinafter, a basic principle of the method of drying the
clothes dryer according to an embodiment of the present invention
will now be described with reference to FIG. 4.
[0036] As the drying operation is performed, the water content of a
drying material loaded in the drum decreases over time. Also, the
temperature of the drying material continuously changes as the hot
air supplied to the drum absorbs moisture of the drying material.
The temperature change occurs through several processes illustrated
in FIG. 4.
[0037] First, a first process (I) is a preheating process of
preheating the drying material to a predetermined temperature or
higher. In the first process (I), the water content of the drying
material decreases while its temperature increases. In this case,
the gradient of the water content gently decreases.
[0038] Next, a second process (II) id a constant rate drying
period, that is, an isothermal drying period in which the
temperature of the drying material is not changed. Since thermal
energy generated from the heater is used as evaporation energy for
drying moisture of the drying material in the second process (II),
the water content of the drying material decreases, whereas the
temperature of the drying material is constant. Thus, the
temperature change of the drying material is almost zero, and the
gradient of the water content becomes constant.
[0039] Finally, in a third process (III), energy of the heater
(i.e., energy of hot air supplied to the drum) is converted into
preheating energy increasing the temperature of the drying
material, and thus the temperature of the drying material sharply
rises. In the third process (III), the water content of the drying
material gently decreases, and this corresponding period may be
considered a decreasing rate drying period.
[0040] The method of drying the clothes dryer according to the
present invention, in order to predict the water content change of
the drying material on the basis of the temperature change of the
drying material, the sensor placed toward an exhaust port of the
drum detects the temperature of the exhaust air. When a heater
caloric value is modulated on the basis of the temperature change
pattern over time, the drying operation may be performed in an
automatic drying mode proper to the dried condition of the drying
material.
[0041] If the water content at the time point when the gradient of
the water content, which is constant, starts to fall, that is, when
the process is changed from the second process (II) to the third
process (III) is defined as a marginal water content, and the water
content at a spot where the change curve of the temperature
(material temperature) of the drying material meets a straight line
where the water content gradient is fixed is defined as a marginal
preheating point, it is experimentally confirmed that almost the
same water content is obtained at the marginal preheating point,
regardless of the amount of the drying material.
[0042] FIGS. 5A and 5B are graphs showing a water content change
and a temperature change of a drying material during a drying
operation for 1 Kg of drying material, and 5 Kg of drying material,
respectively. Similar temperature changes and water content changes
with respect to the respective drying materials are measured. As a
result of determining the water content on the basis of the
temperature of the air coming out of the drum as the drying
material containing moisture is dried, the temperature of the dryer
(i.e., temperature of the drying material) increases at an initial
stage of the drying operation, and then, the temperature of the air
exhausted from the drum is linearly maintained at a middle stage of
the drying operation, i.e., during the constant rate drying period
since thermal energy from the heater evaporators moisture of the
drying material. At a final stage of the drying operation, i.e.,
during the decreasing rate drying period, the thermal energy
increases the temperature of the drying material and the
temperature of the air exhausted to the outside through the exhaust
port is also increased since the drying material has almost no
moisture.
[0043] In comparison of the water contents at the marginal
preheating point from the measured result, it can be seen that
about 18% of water content is measured with respect to both 1 Kg of
drying material and 5 Kg of drying material.
[0044] Accordingly, the air temperature change is measured using
the sensor placed at an exhaust path through which the air is
exhausted from the drum, and the detected temperature change is
analyzed so that the drying operation is executed by setting an
automatic drying mode with reference to the time point when the
temperature change rate is constant, and the time point when the
temperature change rate increases from the constant change rate
value. Consequently, the drying operation can be performed
constantly, regardless of the amount of drying material loaded in
the drum.
[0045] Thus, the present invention is characterized in that the
controller determines a change rate of the air temperature, that
is, a gradient change in the air temperature change graph on the
basis of air temperature data provided from the sensor in order to
determine individual drying periods during the drying
operation.
[0046] The present invention is also characterized in that accurate
temperature change data is obtained by obtaining the gradient of
the temperature change as a moving average.
[0047] The temperature change data can be obtained by increasing
the gradient of the temperature change during a unit time (unit
period), for example, for 10 seconds, in units of one second. That
is, the average gradient value is obtained according to time moving
in order of an initial start time point.about.10 seconds (a first
period), 2 seconds.about.11 seconds (a second period), 3
seconds.about.12 seconds (a third period), . . . , n
seconds.about.n+10 seconds (n period), and the gradient of the air
temperature change in the exhaust port is determined on the basis
of the obtained data.
[0048] The moving average is obtained by the following equation
such that the gradient change (A gradient) is obtained using the
maximum gradient (Max) and the minimum gradient (Min) with respect
to the unit time (unit period) (T).
.DELTA. gradient=(Max(T)-Min(T))/T
[0049] FIG. 6 is a graph showing the gradient change value during
an actual drying operation. The temperature change gradient change
is somewhat unsteady during an initial drying process, and
decreases up to the time point B after the time point A. This
period is a preheating period of a drying material. In the
preheating period, the temperature of the drying material
increases, while the increasing rate of the temperature change
gradually slows. Then, the temperature of the drying material is
constant until the time point C, and thus the gradient of the
temperature change is almost fixed. Thereafter, the temperature of
the drying material keeps increasing, and the gradient of the
temperature change gradually increases.
[0050] During the drying operation, the time point for decreasing
the heat radiation level of the heater or stopping the operation
thereof may be determined at the time point when the moving average
increases from a constant value (specifically, the time point C in
FIG. 6).
[0051] According to the present invention, the water content (FMC)
of the drying material varies according to a drying mode, so that
the drying can be made through various drying modes. Table 1 below
shows an exemplary drying mode.
TABLE-US-00001 TABLE 1 Various drying modes Middle Additional
Initial drying drying Final drying drying General 10% < FMC <
5% < FMC, FMC < 6% FMC < 4% mode 28% 15% Speedy FMC < 7
mode
[0052] FIG. 7 is a flow chart exemplary showing a drying method of
a clothes dryer according to the present invention. When a drying
operation is started (S1), the maximum value (.DELTA.init) of a
gradient of an exhaust-port temperature change is obtained at an
initial stage (e.g., 0.about.3 miniute period) (S20). The gradient
of the temperature change is obtained by the aforementioned moving
average obtaining method. When it is determined that .DELTA.init is
smaller than a predetermined value (e.g., 15) (S3), the next
process is performed to continuously obtain the gradient of the
temperature change. When .DELTA.init becomes greater than the
predetermined value, it is determined that there is no load, that
is, no material to be dried (S4'), and the operation of the heater
is stopped to perform cool air drying (S8). When the temperature
change gradient becomes constant during the drying operation, it is
determined that the current period corresponds to a middle stage
starting point (.DELTA.linear) (S4), and the next process is
performed. The middle stage starting point (.DELTA.linear) may be
set to about a middle point (.DELTA.init/3) between the initial and
middle stages. In the next process, the time point when the
gradient of the temperature change increases is determined as a
start point (.DELTA.overshoot) of a final stage of the drying (S5),
and the next process is performed. The start point
(.DELTA.overshoot) of the final stage of the drying may be set to,
for example, about a middle point (.DELTA.init/2) between the
middle and final stages of the drying. When a predetermined time
elapses (.DELTA.Time) (S6), the drying operation may be performed
in each automatic drying mode pre-selected by a consumer
(S7a.about.S7b).
[0053] The drying operation according to the present invention may
be very consistent and uniform regardless of a kind or amount of
drying materials, by detecting the temperature change of the air
exhausted from the drum and analyzing the gradient change of the
temperature change. Also, such a drying method may be applied not
only to the clothes dryer but also to a washing machine with dryer.
Also, only a sensor and a drying mode controller are installed
without any complicated element, so that the drying can be
performed more smoothly and accurately.
[0054] As described so far, the control method of the clothes dryer
according to an embodiment of the present invention may allow an
accurate drying operation since the air temperature in the exhaust
port of the drum is measured, and a water content or a temperature
is determined on the basis of data about the gradient of the air
temperature change. The present invention may be applied to both a
clothes dryer and a washing machine with a dryer in the same
manner, and allows effective automatic drying, regardless of a kind
and amount of a drying material.
[0055] As the present invention may be embodied in several forms
without departing from the spirit or essential characteristics
thereof, it should also be understood that the above-described
embodiments are not limited by any of the details of the foregoing
description, unless otherwise specified, but rather should be
construed broadly within its spirit and scope as defined in the
appended claims, and therefore all changes and modifications that
fall within the metes and bounds of the claims, or equivalents of
such metes and bounds are therefore intended to be embraced by the
appended claims.
* * * * *